The present invention relates to a method for bending and forming a composite material sheet, such as a resin-impregnated, fiber reinforced composite material sheet containing laminated meshes of fibers, and to an apparatus for such bending and forming. More specifically, the invention relates to a method and apparatus for bending and forming a composite material sheet without formation of creases and lines even in the case when there is a curved contour along edges linking a reference surface and flange surfaces of the formed product.
Conventionally, as a method for forming a prepregnated, fiber reinforced composite material sheet containing fibers laminated into a mesh, a method is known such as that disclosed in Japanese Patent Application Laid-Open Publication No. 59-129119, wherein a composite material is conveyed manually sheet by sheet to a forming die and is laminated. Another known method is such as that disclosed in Japanese Utility Model Appln. No. 62-26838 wherein vacuum is used in conjunction with a vacuum bag and side blocks to perform the forming.
Among these conventional forming methods described above, the former method that involves manual laminating by human labor so that deviation occurs in the quality of the formed products and heavy labor is needed when the number of lamination processes increases. In addition to this, when there is laminating with curves, complex hand movements and skill are required in order to form the desired form. There are also the problems of the work time being long and consequently the time limit for effective use of the prepregnated material becoming shorter, therefore making it difficult to laminate large products.
On the other hand, with the latter method involving the vacuum bag, there is the possibility that the work time for the lamination can be reduced and large products can be laminated, but there are instances wherein the force that presses the prepregnated material and the vacuum bag against the side blocks does not operate when the side blocks are lowered, and this creates the problem of creases being formed in portions where the prepregnated material is bent.
In addition, in both of these two conventional methods, there is the problem of creases and lines being formed when bending and forming are performed for a composite material having an undulated reference surface or having curved lines along the edges linking the reference surface and flange surfaces.